Leetcode二叉树的前、中、后序遍历

Every day a leetcode 递归实现二叉树的前、中、后序遍历。
前序遍历题目来源：144. 二叉树的前序遍历
代码：
/** * Definition for a binary tree node. * struct TreeNode { *int val; *struct TreeNode *left; *struct TreeNode *right; * }; *//** * Note: The returned array must be malloced, assume caller calls free(). */#define MAX_NODE_SIZE 100void preOrder(struct TreeNode* root,int* ans,int* ansSize){if(root == NULL) return;ans[(*ansSize)++]=root->val;preOrder(root->left,ans,ansSize);preOrder(root->right,ans,ansSize);}int* preorderTraversal(struct TreeNode* root, int* returnSize){*returnSize=0;int* ans=malloc(MAX_NODE_SIZE*sizeof(int));preOrder(root,ans,returnSize);return ans;} 【Leetcode二叉树的前、中、后序遍历】结果：
中序遍历题目来源：94. 二叉树的中序遍历
代码：
/** * Definition for a binary tree node. * struct TreeNode { *int val; *struct TreeNode *left; *struct TreeNode *right; * }; *//** * Note: The returned array must be malloced, assume caller calls free(). */#define MAX_NODE_SZIE 100void inOrder(struct TreeNode* root,int* ans,int* ansSize){if(root == NULL) return;inOrder(root->left,ans,ansSize);ans[(*ansSize)++]=root->val;inOrder(root->right,ans,ansSize);}int* inorderTraversal(struct TreeNode* root, int* returnSize){*returnSize=0;int *ans=malloc(MAX_NODE_SZIE*sizeof(int));inOrder(root,ans,returnSize);return ans;} 结果：
后序遍历题目来源：145. 二叉树的后序遍历
代码：
/** * Definition for a binary tree node. * struct TreeNode { *int val; *struct TreeNode *left; *struct TreeNode *right; * }; *//** * Note: The returned array must be malloced, assume caller calls free(). */#define MAX_NODE_SZIE 100void postOrder(struct TreeNode* root,int* ans,int* ansSize){if(root == NULL) return;postOrder(root->left,ans,ansSize);postOrder(root->right,ans,ansSize);ans[(*ansSize)++]=root->val;}int* postorderTraversal(struct TreeNode* root, int* returnSize){*returnSize=0;int *ans=malloc(MAX_NODE_SZIE*sizeof(int));postOrder(root,ans,returnSize);return ans;} 结果：